Mechanism for expanding a honing tool

ABSTRACT

A rapid traverse motor drives a hone expanding shaft at a comparatively fast rate until the stones of the hone engage the work at which time this motor is stopped and a feed motor turns the shaft at a slower rate. Between the rapid traverse motor and the shaft and isolated from the drive motor is a resilient connection in the form of a torsion spring which prevents inertial rotation of the rapid traverse motor, once that motor has been inactivated, from being transmitted to the shaft.

O United States Patent 1 [111 3,736,703 Estabrook et al. 51 June 5, 1973 541 MECHANISM FOR EXPANDING A 2,781,616 2 1957 Estabrook ..51 34 D x HONING TOOL 3,369,327 2/1968 Estabrook ..51 34 J 3,404,490 10/1968 Estabrook ..51/34 D X [75] Inventors: Mark R. Estabrook, Rockford, 111.; 3,466,809 9/1969 Estabrook ..51/l65.77

Wilfred F. W. Treder, Beloit, Wis.

73 Assignee: Barnes Drill '00., Rockford, 111. Primary Examiner-Harold Whitehead AttorneyWolfe, Hubbard, Leydig, Voit & Osann, [22] Filed: Aug. 27, 1971 [21] App1.No.: 175,430

Related US. Application Data [57] ABSTRACT A rapid traverse motor drives a hone expanding shaft [63] Continuation-mp8" of at a comparatively fast rate until the stones of the 1970, abandoned,

hone engage the work at Wl'llCll time this motor is stopped and a feed motor turns the shaft at a slower [52] US. Cl ..51/165.8, 51/34 D rate Between the rapid traverse motor and the Shaft [51] II."- Cl. and isolated from the drive motor is a resilient [58] Field of Search 51/34 C-34 K, nection in the form of a torsion Spring which prevents R, 165-8 inertial rotation of the rapid traverse motor, once that motor has been inactivated, from being transmitted to [56] References Cited the shaft.

UNITED STATES PATENTS 6 Claims, 7 Drawing Figures 2,780,839 2/1957 Seborg et a1 ..51/34 D PATENIEDJUH 5 I975 SHEET 1 [IF 3 PATENTEDJUH 5191s 3.736.703

FIG 7 1 MECHANISM FOR EXPANDING A HONING TOOL CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of our copending application Ser. No. 10,757, filed Feb. 12, 1970 and now abandoned.

BACKGROUND OF THE INVENTION In the usual honing machine, the honing tool is expanded, that is, the stones of the tool are moved radially outwardly, by turning a shaft which shifts the expanding cams in the tool. When the tool is first inserted in the bore of the work to be honed, it is in the collapsed condition and is expanded comparatively fast by a rapid traverse motor which turns the shaft. This continues until the stones engage the work at which time the rapid traverse motor is deactivated and a feed motor is activated to turn the shaft at a relatively slow speed during the honing operation. When the rapid traverse motor is deactivated, it tends to continue turning briefly due to inertia. If the effect of this inertial rotation were transmitted to the expanding cams, the stones would impact against the work and could be crushed. To overcome this, the drive to the cams has included a connection, such as a shock-absorbing lost motion connection, to take up the inertial rotation of the rapid traverse motor before the feed motor becomes effective to expand the honing tool.

SUMMARY OF THE INVENTION The general object of the invention is to provide a new and improved drive for a hone expanding mechanism which prevents the inertial rotation of the rapid traverse motor from being transmitted to the expanding cams while permitting the feed motor to become effective immediately upon deactivation of the rapid traverse motor so as to reduce the overall time of the work cycle and to reduce the possibility of the honing stones being glazed due to idle rotation while in contact with the work.

A more detailed object is to achieve the foregoing by interposing a resilient connection in the drive between the rapid traverse motor and the hone expanding shaft and by isolating this connection from the drive between the feed motor and the shaft.

The invention also resides in the particular construction of the resilient connection and its interposition in the drive between the rapid traverse motor and the hone expanding shaft.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary schematic view of a honing machine incorporating the novel resilient connection of the present invention.

FIG. 2 is an enlarged fragmentary view of a portion of the machine, parts being broken away and shown in section.

FIG. 3 is a perspective view of the resilient connection.

FIG. 4 is a sectional view taken along the line 4-4 in FIG. 2.

FIG. 5 is a view similar to FIG. 4 but shows the parts in a moved position.

FIG. 6 is an exploded view of the resilient connection.

FIG. 7 is a schematic view of a control circuit.

DETAILED DESCRIPTION OF THE lRL-lFliRRlil) EMBODIMENT As shown in the drawings for purposes of illustration, the invention is embodied in a honing machine for honing the bore 10 of a workpiece 11. The machine includes the usual tool 12 which comprises a plurality of stones 13 mounted on a body 14 and angularly spaced around the body. The latter is fixed to a tubular shaft 15 journaled in a head 16 which is slidably mounted on a column (not shown) for reciprocation by a piston 17 acting in a cylinder 18 so that the tool 12 is reciprocated in the bore 10 during the honing cycle. As the tool is reciprocated, it also is rotated by a motor 19 mounted on the head and driving the shaft 15. For this purpose, a gear 20 on the output shaft of the motor 19 meshes with a gear 21 fast on one end of a shaft 22 journaled in the head 16 and a gear 23 on the other end of this shaft meshes with a gear 24 fixed on the shaft 15.

As is customary in machines of this type, the stones 13 are mounted on the tool body 14 to move radially inwardly and outwardly and are urged toward their innermost or collapsed position by springs (not shown). The stones are moved out into engagement with the wall of the bore 10 and then are fed outwardly into the work during the honing operation by conical cams 25 which act on the back of the stones in a manner wellknown in the art. The cams are mounted on the end of a rod or shaft 26 which is concentrically disposed within the hollow shaft 15 and the upper end portion 27 of the shaft 26 projects beyond the end of the shaft 15 and is threaded into a gear 28 journaled in the housing. A rapid traverse motor 29 and a feed motor 30 are mounted in the head 16 and, through a control mechanism 31, a selected one of the motors turns a shaft 32. The latter carries a gear 33 which meshes with the gear 28 and completes the drive between the rod 26 and either of the motors 29 and 30, whichever is operative at the time.

At the beginning of the honing cycle, the tool 12 is fully collapsed as it enters the bore 10. The control mechanism 31 is activated so that the rapid traverse motor 29 drives the shaft 32 and this expands the tool at a comparatively fast rate until the stones 13 engage the walls of the bore. At that time, the control mechanism deactivates the rapid traverse motor and activates the feed motor 30 to expand the tool slowly during the working portion of the honing cycle. To sense when the stones engage the wall of the bore, a digital pick-up element 34 is mounted in the head 16 alongside the gear 28 and senses the rate at which the teeth of the gear pass the element. When the stones l3 engage the wall of the bore 10, the rotation of the gear 24 slows down and this is detected by the element 34. When the latter senses that the rotation of the gear 24 has reduced to a preselected speed due to the stones engaging the work, it activates the control mechanism 31 to deactivate the rapid traverse motor 29 and activate the feed motor 30. When the rapid traverse motor is inactivated, it continues to rotate briefly due to inertia and, if this inertial rotation were transmitted to the expanding cones 25, the stones 13 could be crushed against the wall of the bore 10. One way of avoiding this inertial effect is to interpose a shock-absorbing lost motion connection 35 (FIG. 2) in the drive to the cams 25.

In accordance with the present invention, the shockabsorbing lost motion connection 35 is constructed and located in a novel manner which not only eliminates the inertial effect of the rapid traverse motor 29 but also permits the feed motor 30 to become effective immediately upon deactivation of the rapid traverse motor and thereby eliminates idle rotation of the tool 12. Eliminating this idle rotation reduces the overall time of the honing cycle and minimizes the chances of the stones 13 being glazed by turning in the bore 16 while only lightly engaging the bore wall. To this end, the connection is a resilient connection interposed between the rapid traverse motor and the hone expanding shaft 32 and isolated from the drive between the feed motor and this shaft. More specifically, the resilient connection 35 is driven by the rapid traverse motor and drives a gear 36 keyed to the shaft 32 while the feed motor drives the shaft 32 directly.

In this instance, both the rapid traverse motor 29 and the feed motor 30 are hydraulic motors and are mounted on a support 37 (FIG. 2) which is in the head 16. On the shaft 38 of the feed motor is a worm gear 39 meshing with a worm wheel 46 keyed to a shaft 41 journaled in bearings 42 on the support 37. Splined on one end of the shaft 41 is a plate 42a which constitutes the driving element of an electromagnetic clutch 43. The driven element'of the clutch includes an annulus 44 of friction material seated in a ring 45 keyed to the shaft 32 which is journaled on the support 37 by bearings 416 and 47. Also carried by the ring 45 is a coil 48 which, when energized, draws the plate 42a into engagement with the annulus 44 and thus engages the clutch 43 so that the feed motor 36 drives the shaft 32 and thus directly advances the earns 25.

The resilient connection 35 between the rapid traverse motor 29 and the shaft 32 includes a torsion spring 49 which transmits the rotation of the shaft 50 of the motor 29 to a gear 51 which meshes with an idler gear 52 journaled on the support by bearings 53, the idler gear meshing with the gear 36 on the shaft 32. l-lerein, the torsion spring 4-9 is a coiled spring with one end 54 anchored in a cap 55 which is fastened by a screw 56 to a sleeve 57 which, by means of a key 58, is secured to the shaft 56 of the rapid traverse motor 29. .lournaled on the sleeve 57 by a bushing 59 is an annulus 60 and the gear 5B. is seated on a shoulder 61 on the annulus 60 and fastened to the latter by a screw 62. Fastened to the annulus 66 by a screw 63 is a dog 64! and the other end 65 of the spring 49 is anchored in the dog in an aperture 65a.

As shown in FIGS. 4 and 6, the sleeve 57 is formed with an arcuate slot 78 and the. ear 66 of the dog 66 projects into this slot. This spring 49 is wound tight enough, but not fully wound, so that it holds the ear 66 against the end wall 67 of the slot during normal operation of the rapid traverse motor 29. Thus, when the motor 29 is activated, the sleeve 57 turns with the motor shaft 56 and the spring 49 holds the ear 66 against the wall 67. As a result, the dog 64 and hence the annulus 60 and the gear 51 turn with the motor shaft 30 and the shaft 32 is driven by the rapid traverse motor 29. When the rapid traverse motor 29 is deactivated, the gear 51 and the dog 64 stop immediately. The inertia of the motor 29, however, causes the shaft 36 and the sleeve 37 to continue turning momentarily and the wall 67 turns away from the ear 66 as shown in FIG. 5. This inertial rotation of the motor 29 winds the spring further but, when terminated, the spring 49 turns the shaft 50 and the sleeve 57 back until the wall 67 engages the ear 66. In this way, the over-travel and return of the rapid traverse shaft 50 has no effect on the shaft 32. t

For ease of assembly and to adjust the torsional force of the spring 49, the cap 55 is formed with serrations or teeth 68 which mate with corresponding teeth 69 on the adjacent end of the sleeve 57. When assembling the connection 35, the screw 56 is loose so that the cap 55 may be turned relative to the sleeve 57 to wind up the spring 49 the desired amount. When this has been achieved, the screw 56 is tightened to mesh the teeth 68 and 69 and the cap 55 and the sleeve 57 thereby become a rigid assembly.

FIG. 7 shows schematically a suitable circuit for controlling the change from the rapid traverse motor 29 to the feed motor 19 in response to a reduction in the speed of rotation of the gear 28. The rapid traverse motor 29 is connected to a direct current source 78 through normally closed switches 71 and the feed motor 19 is connected to this source through normally open switches 72, the switches 71 and 72 being connected to the armature 73 of a relay 74. The digital sensor 34 produces pulses in the usual manner at a rate corresponding to rate of rotation of the gear 28. These pulses are fed to a pulse shaper 75 which gives the pulses a uniform shape and the output of the pulse shaper 75 is fed to a conventional averaging filter 76 which produces a direct current of a magnitude corresponding to the rate of pulses produced by the digital sensor 34. The direct current from the averaging filter 76 is fed to a standard threshold circuit 77 whose output is connected to the relay 74. When the magnitude of the direct current from the averaging filter 76 drops below a preselected value due to the slowing of the gear 28, the threshold circuit 77 energizes the solenoid 74. This opens the switches 71 and closes the switches 72 thus deenergizing the rapid traverse motor 29 and energizing the feed motor 19.

in operation, the tool 112 is collapsed and retracted at the beginning of a cycle. With the work 11 in place, the motor 19 rotates the tool 12 through the gears 26, 211, 23 and 24 and the hollow shaft 15 and the piston l7 lowers the head 16 thereby lowering the tool in the bore 116. At this time, the rapid traverse motor 29 is energized and the clutch 43 is disengaged so that the feed motor 38 is inactive. As a result, the motor 29 shifts the cams 25 through the resilient connection 35, the shaft 32, the gears 33 and 28, and the rod 26. As a result, the tool is expanded quite rapidly until the stones 13 engage the wall of the bore. When this condition is sensed by the element 36, the control circuit shown in FIG. 7 simultaneously deenergizes the rapid traverse motor 29 and energizes the coil 48 to engage the clutch 43 so that the tool continues to expand under the control of the feed motor 36.

During the rapid expansion of the tool E2, the spring 49 in the resilient connection 35 holds the car 66 of the dog 64 against the shoulder 67 on the sleeve 57 as shown in PEG. 4 and this transmits the rotation of the rapid traverse motor 29 to the shaft 32. When the sensing element 36 deenergizes the rapid traverse motor 29 and engages the clutch 43, the dog 64 no longer is under the control of the rapid traverse motor 29 but, instead, is turned at a slower rate by the feed motor 36 through the gears 36, 52 and 51. At the time of changeover, however, the inertia of the rapid traverse motor 29 may cause the shoulder 67 on the sleeve 57 to move 4 away from the car 66 as shown in FIG. 5. This winds the spring 49 further and, when the inertial effect of the motor 29 is expended, the spring returns the sleeve 57 so that the shoulder 67 again abuts the ear 66 and the parts again are positioned relatively to each other as shown in FIG.-4.

During the time the shoulder 67 moves away from the ear 66, returns into engagement with the ear and thereafter, the rapid traverse motor has no effect on the shaft 32. This permits the feed motor 30 to be activated, herein by engagement of the clutch 43, at the same time that the rapid traverse motor is deactivated. As a result, the change-over to the feed motor does not cause any lost time in the overall cycle and, because the tool 12 always is being expanded by one or the other of the motors 29 and 30, the chance of the stones 13 being glazed by idle rotation in light contact with the wall of the bore is minimized.

We claim as our invention:

1. In a honing machine having a tool, means for expanding the tool, and a shaft operable when turned to activate said expanding means, the combination of, a rapid traverse motor, means including a resilient connection between said motor and said shaft whereby the motor when activated causes rapid expansion of the tool, a feed motor, a second connection between said feed motor and said shaft whereby the feed motor when activated causes slow expansion of the tool, and means responsive to the tool engaging a workpiece and operable to inactivate said rapid traverse motor and simultaneously activate said feed motor, said resilient connecing a resilient connection between said motor and said second gear whereby the motor when activated causes rapid expansion of the tool, a feed motor, a second connection between said feed motor and said shaft whereby the feed motor when activated causes slow ex pansion of the tool, and means responsive to the tool engaging a workpiece and operable to inactivate said rapid traverse motor and simultaneously activate said feed motor, said resilient connection being isolated from said second connection and permitting inertial rotation of said rapid traverse motor without transmitting such rotation to said shaft.

3. In a honing machine having a tool, means for expanding the tool, and a rotatable shaft operable when turned to activate said expanding means, the combination of, a motor, a rotatable member driven by said motor, a first gear concentric with and journaled on said member and having a first abutment, said member having a second abutment engageable with said first abutment, a torsion spring having one end anchored to said member and the other end anchored to said gear, said spring normally holding said first abutment against said second abutment whereby said member turned said gear through said spring and said spring permits said second abutment to move away from said first abutment, and a second gear fixed to said shaft and driven by said first gear whereby inertial rotation of said motor causes said second abutment to move away from said first abutment when said motor is inactivated and the speed of rotation of said shaft is reduced.

4. Apparatus as defined in claim 3 in which said second abutment is the end wall of an arcuate slot in said member and said first abutment is a finger projecting radially inwardly into said slot.

5. Apparatus as defined in claim 4 in which said torsion spring is a coiled spring.

6. Apparatus as defined in claim 3 in which said torsion spring is a coiled spring encircling said member. 

1. In a honing machine having a tool, means for expanding the tool, and a shaft operable when turned to activate said expanding means, the combination of, a rapid traverse motor, means including a resilient connection between said motor and said shaft whereby the motor when activated causes rapid expansion of the tool, a feed motor, a second connection between said feed motor and said shaft whereby the feed motor when activated causes slow expAnsion of the tool, and means responsive to the tool engaging a workpiece and operable to inactivate said rapid traverse motor and simultaneously activate said feed motor, said resilient connection being isolated from said second connection and permitting inertial rotation of said rapid traverse motor without transmitting such rotation to said shaft.
 2. In a honing machine having a tool, means for expanding the tool, and a shaft operable when turned to activate said expanding means, the combination of, a rapid traverse motor, a first gear fixed to said shaft, a second gear meshing with said first gear, means including a resilient connection between said motor and said second gear whereby the motor when activated causes rapid expansion of the tool, a feed motor, a second connection between said feed motor and said shaft whereby the feed motor when activated causes slow expansion of the tool, and means responsive to the tool engaging a workpiece and operable to inactivate said rapid traverse motor and simultaneously activate said feed motor, said resilient connection being isolated from said second connection and permitting inertial rotation of said rapid traverse motor without transmitting such rotation to said shaft.
 3. In a honing machine having a tool, means for expanding the tool, and a rotatable shaft operable when turned to activate said expanding means, the combination of, a motor, a rotatable member driven by said motor, a first gear concentric with and journaled on said member and having a first abutment, said member having a second abutment engageable with said first abutment, a torsion spring having one end anchored to said member and the other end anchored to said gear, said spring normally holding said first abutment against said second abutment whereby said member turned said gear through said spring and said spring permits said second abutment to move away from said first abutment, and a second gear fixed to said shaft and driven by said first gear whereby inertial rotation of said motor causes said second abutment to move away from said first abutment when said motor is inactivated and the speed of rotation of said shaft is reduced.
 4. Apparatus as defined in claim 3 in which said second abutment is the end wall of an arcuate slot in said member and said first abutment is a finger projecting radially inwardly into said slot.
 5. Apparatus as defined in claim 4 in which said torsion spring is a coiled spring.
 6. Apparatus as defined in claim 3 in which said torsion spring is a coiled spring encircling said member. 